1. Field of the Invention
Exemplary aspects of the present invention generally relate to an image extraction device, and more particularly, to an image extraction device that extracts an image of a document from a shot image shot by an imaging device.
2. Description of the Background Art
Conventionally, in a meeting or the like, a document camera or an overhead camera (hereinafter referred to as a document camera) is used to project an image of a document placed on a document table of the document camera onto a projection screen or a monitor. In order to show the document image on the projection screen or the monitor, an image extraction device is employed to segment the document image from a shot image shot by an imaging device of the document camera. Such an image extraction device allows participants in the meeting to share the same document as well as any handwritten information added to the document during the meeting with ease.
One example of such a known image extraction device detects the contours of the document table using as a reference from a shot image of the document table taken when no document was placed thereon. The contours of the document table are then registered. Subsequently, the document camera masks the registered contours of the document table to acquire the contours of the document placed thereon.
Although advantageous, there is a drawback to this approach in that, since the image of the document is extracted by detecting the contours of the entire document placed on the document table, the entire document needs to be properly placed on the document table. Otherwise, the image showing the entire document cannot be extracted properly.
In view of the above, a device capable of extracting an image showing the entire document is required even when only a portion of the document is placed on the document table of the document camera.